Can I leave after serving 2 months notice period, since I didn't acknowledge the updated notice period

I am currently serving my notice period of 3 months, in the offer letter which was signed by me and the employer it states that notice period will be of 2 months, but recently before my resignation they updated their notice period to 3 months and sent an email to all the employees informing about this buy they did not ask any acknowledgement on that email.
Can I leave after serving 2 months, since I have not acknowledged the updated notice period and the one that is mentioned on offer letter is 2 months.

I have served half of the notice period and also tried to buy out my notice period but my employer declined my request to buy out.
1. Is it right of the employee to leave the organisation by paying for the days they are not serving notice for or is it under employer's hand to allow and deny buyout of notice period.
2. Can the employer deny issuing relieving letter and experience letter even after paying the salary for the days not served.
Below are some points from employee manual, are any of these points not according to the rights for an employee during notice period.
▪ In case proper notice period is not served as per the policies, the employee will be liable to pay back the
salary for the number of days not served.
▪ Relieving letter and experience letter will be issued to only those employees who follow the policy and serve
proper notice period.